Gas Discharge Lamps - Color

Color

Each gas, depending on its atomic structure emits certain wavelengths which translates in different colors of the lamp. As a way of evaluating the ability of a light source to reproduce the colors of various objects being lit by the source, the International Commission on Illumination (CIE) introduced the color rendering index. Some gas-discharge lamps have a relatively low CRI, which means colors they illuminate appear substantially different than they do under sunlight or other high-CRI illumination.

Gas Color Spectrum Notes Image
Helium White to orange; under some conditions may be gray, blue, or green-blue. Used by artists for special purpose lighting.
Neon Red-orange Intense light. Used frequently in neon signs and neon lamps.
Argon Violet to pale lavender blue Often used together with mercury vapor.
Krypton Gray off-white to green. At high peak currents, bright blue-white. Used by artists for special purpose lighting.
Xenon Gray or blue-gray dim white. At high peak currents, very bright green-blue. Used in flashbulbs, xenon HID headlamps, and xenon arc lamps.
Nitrogen Similar to argon but duller, more pink; at high peak currents bright blue-white.
Oxygen Violet to lavender, dimmer than argon
Hydrogen Lavender at low currents, pink to magenta over 10 mA
Water vapor Similar to hydrogen, dimmer
Carbon dioxide Blue-white to pink, in lower currents brighter than xenon Used in Carbon Dioxide Lasers.
Mercury vapor Light blue, intense ultraviolet

Ultraviolet not shown

In combination with phosphors used to generate many colors of light. Widely used in mercury-vapor lamps.
Sodium vapor (low pressure) Bright orange-yellow Widely used in sodium vapor lamps.

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